tailieunhanh - Báo cáo khoa học: Presence of membrane ecdysone receptor in the anterior silk gland of the silkworm Bombyx mori

Nongenomic action of an insect steroid hormone, 20-hy-droxyecdysone (20E), has been implicated in several 20E-dependent events including the programmed cell death of Bombyxanterior silk glands (ASGs), but no information is available for themodeof evidence for a putative membrane receptor located in the plasma mem-brane of the ASGs. Membrane fractions prepared from the ASGs exhibit high binding activity to [ 3 H]ponasterone A (PonA). The membrane fractions did not contain conven-tional ecdysone receptor as revealedbyWesternblot analysis using antibody raised againstBombyxecdysone receptor A (EcR-A) | Eur. J. Biochem. 271 3171-3179 2004 FEBS 2004 doi Presence of membrane ecdysone receptor in the anterior silk gland of the silkworm Bombyxmori Mohamed Elmogy Masafumi Iwami and Sho Sakurai Division of Life Sciences Graduate School of Natural Science and Technology Kanazawa University Kakumamachi Japan Nongenomic action of an insect steroid hormone 20-hy-droxyecdysone 20E has been implicated in several 20E-dependent events including the programmed cell death of Bombyx anterior silk glands ASGs but no information is available for the mode of the action. We provide evidence for a putative membrane receptor located in the plasma membrane of the ASGs. Membrane fractions prepared from the ASGs exhibit high binding activity to 3H ponasterone A PonA . The membrane fractions did not contain conventional ecdysone receptor as revealed by Western blot analysis using antibody raised against Bombyx ecdysone receptor A EcR-A . The binding activity was not solubilized with 1 M NaCl or w v MEGA-8 indicating that the binding sites were localized in the membrane. Differential solubilization and temperature-induced phase separation in Triton X-114 showed that the binding sites might be integrated membrane proteins. These results indicated that the binding sites are located in plasma membrane proteins which we putatively referred to as membrane ecdysone receptor mEcR . The mEcR exhibited saturable binding for 3H PonA Kd nM Bmax pmol-mg-1 protein . Association and dissociation kinetics revealed that 3H PonA associated with and dissociated from mEcR within minutes. The combined results support the existence of a plasmalemmal ecdysteroid receptor which may act in concert with the conventional EcR in various 20E-depend-ent developmental events. Keywords ecdysone agonist ecdysone receptor kinetics nongenomic ponasterone A. Steroids elicit various physiological responses particularly those involving the genomic aspects of action in which they .